Vinyl ethers chromium chloride

Recently it was found that ot-trichloromethyl carbinols and their ethers, a class of compounds which is easily obtainable in large structural variety, can be reduced by chromium(II) chloride in water or aqueous DMF to synthetically very interesting products (Table 5, No. 6-8) . Thus, trichloromethyl-substituted secondary alcohols and ethers give (Z)-configurated vinyl chlorides in one step (Eqs. (70)-(72)). 

To a flask was added 200 mg chromium(II) chloride (1.63 mmol, 2.5 eq.) then 2.5 mL THF was added under vigorous stirring. After a few minutes, 229 mg benzaldehyde (2.16 mmol, 3.0 eq.) and 156.3 mg 3,7-dimethyl-l-bromo-oct-2,6-diene (0.72 mmol, 1.0 eq.) were added. The resulting mixture was stirred for 3 h at 55" C, and the reaction was quenched with brine. The aqueous layer was extracted three times with diethyl ether, and the combined organic fractions were washed twice with brine, dried over MgS04, and concentrated in vacuo. The residue was purified by silica gel column chromatography using diethyl ether as the eluent, to afford 64% 2,6-dimethyl-l-phenyl-2-vinyl-hept-5-en-l-one as a colorless oil, in a yield of 64%, Rf = 0.64 (hexane/EtOAc, 98 2). 

Other polymers which have been the subject of thermal degradation studies include ethylene-vinyl acetate [29, 66, 67], ethylene-vinyl alcohol [68], poly(aryl-ether ketone) [69], poly-2-vinyl-naphthalene-co-methyl maleate [34], polyphenylenes based on diethyl-benzophenone [70], polyglycollide [71-73], poly(a-methylstyrene tricarbonyl chromium [74], polytetrahydrofuran [75], polylactide [76-78], poly(vinyl) cyclohexane [79], styrene-vinyl cyclohexane [80], isopropenylacetate-maleic dianhydride [80], polyethylene glycol containing a 1,3-disubstituted phenolic group [81], poly-2-vinyl naphthalene-co-methacrylate [34], collagen biopolymers [82], chitin graft poly (2-methyl-oxazoline - polyvinyl chloride blends [83], cellulose [32, 83-88] and side-chain cholestric elastomers [89, 90]. 

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